In recent years, corresponding to the enhancement of semiconductor elements in integration degree, the miniaturization of a pattern of wiring or the like is required. In order to form a fine pattern, a short-wavelength light such as an ArF excimer laser (wavelength: 193 nm) is adopted as a light source for exposure to form a resist pattern.
As the aspect ratio (height/width) of a resist pattern increases, a pattern collapse occurs more easily. In order to prevent the pattern collapse, the film thickness of a resist is necessary to be reduced. However, a resist pattern formed from a resist having a small film thickness may be lost while dry etching a material to be etched using the resist pattern as a mask. In order to prevent the pattern collapse and to form a resist pattern having a desired cross-sectional shape, a resist underlayer film is provided as a base of the resist pattern.
There is known a composition containing a polymer compound containing silicon for forming a resist underlayer film (for example, see Patent Documents 1 to 3). Patent Document 1 discloses two types of compositions for forming a resist underlayer film containing a hydrolysis condensate of an alkoxysilane. Patent Document 2 discloses a material for an anti-reflective coating that contains a polysiloxane having a repeating unit of a copolymerization. Patent Document 3 discloses a silicone resin for an anti-reflective coating, containing an organic group having a carbon-oxygen single bond and/or a carbon-oxygen double bond. However, in any one of Patent Documents 1 to 3, there is no description on a polysilane.
Patent Document 4 discloses a polysilane having excellent heat resistance and an enhanced solubility in a solvent and a production method thereof. However, Patent Document 4 does not indicate that the polysilane is suitable for the application of a resist underlayer film (anti-reflective coating).    [Patent Document 1]
Japanese Patent Application Publication No. JP-A-2004-157469    [Patent Document 2]
Japanese Patent Application Publication No. JP-A-2004-310019    [Patent Document 3]
Japanese Patent Application Publication No. JP-A-2005-015779    [Patent Document 4]
Japanese Patent Application Publication No. JP-A-2007-077198